Method of making a catalytic bed

ABSTRACT

Method for making a catalytic bed for a gas generator by saturating an inert porous support material with a molybdenum resinate and turpentine solution, and decomposing the solution to leave a residue coating on the inert porous support material and thereby form a catalytic bed.

United States Patent 1191 Duncan et al.

[ METHOD OF MAKING A CATALYTIC BED [75] Inventors: William A. Duncan;James A.

Murfree, Jr., both of Huntsville, Ala.

[73] Assignee: The United States of America as represented by theSecretary of the Army, Washington, DC.

[22] Filed: Mar. 28, 1972 [2]] Appl. No.: 238,926

[52] U.S. Cl 252/458, 117/46 CA, 117/46 FA,

117/123 B 511 1m. 01 844d 1/40, 1344a 1/44, B01 j 11/06, 801 11/50 58 1Field of Search 60/219, 220; 149/36;

117/46 CA, 46 FA, 46 PC, 123 A, 123 B; 423/606; 252/458 [56] ReferencesCited UNITED STATES PATENTS 3,608,313 9/1971 Guth et al 60/219 Aug. 28,1973 2,55l,7l2 5/1951 Soby 117/46 CA 2,842,457 7/1958 Morgan et al....117/46 CA 3,189,477 6/1965 Shaffer .1 117/46 CA 2,748,033 5/1956 Gentryet al. 1 17/46 CA Primary Examiner-William D. Martin AssistantExaminer-M. Sofocleous Atmrney- Harry M. Saragovitz, Edward J. Kelly eta1.

[ ABSTRACT the inert porous support material and thereby form acatalytic bed.

4 Claims, No Drawings 3,755,205 1 1 2 METHOI) OF MAKING A CATALYTIC BEDlybdenum resinate and turpentinesolution which lends l V.itselfreadilyto-the ,depositionof auniform coating of 'CROSSREFERENCETo RELATED APPLICATION .true catalytic metalon the surfaceof a porousbed or This application is a division of applicants co- .support suchasinsulating fire brick or various corrui-pe'nding application fSer. No.68,580, filed Aug. 31, 5 gated" ceramics .which have porouswalls. Thesolution 1970. is poured over=the porous bedor support material H B A CKGR N OF THE INVENTION 2;? absorbs the liqui h e a sponge un 11 l is sa uin the past, liquid. gas generators have utilizedinert 'The solutionisthen decomposed by some means,

beds with a catalyst such as the Shell 405 catalyst and such as burning,allowing the. organicpartof the soluinert beds with various oxidizingagents such as 50 -.tion:to'-burn off, but leaving a coating ofmolybdenum HlO "and 'KMnO ,ln these type gas generation and/or theoxides of molybdenum deposited on the surschemes, the catalytic beds arevery expensive, and the "facecof thezbed. or .support. Theygeight ofthe, deposit inert'beds with oxidizing agents'have limitations asgto:may bevaried according tothe number of applications th'e'numberoftimeslthey can be restartedpsome of l 5.as above.

" these arrangements are alsovery expensive'due to the insulating:firebrickrwith a porosity of approximately chemicals used therein.Accordingly, a need exists for 7-3 percentworks well, and insulatingfire brick with a a reliablecatalytic bed that has the ability tocausehyporosity from 50-80% canbe used. Zircon mullite cordrazin'e tospontaneously decompose on a multiplicity I rugated ceramic with awallporosity of 25-30 percent ofstarts of the gas-generator. ..alsoworks-.welhWhen; the mullite ceramic material is Therefore, it is anobject of this invention to provide .-used,-it is used as a multiplicityof turns so that an over- -a' method for producing a true catalytic bedthat utilizes .all'unitary structure of ceramiciwith the spaces definedchemicals that bringabout spontaneous exothermal between each wallhas.an overall porosity of from 60 I and gas producingdecomposition of.hydrazine: type to-90 percent-depending upon the closeness of thewalls=m'onopropellant fuels. .to,each other. "Another object of thisinvention is to provide a Injection of hydrazine (N H onto the coatedsupmethod'for makinga catalyticbed that can beused for port results-inspontaneous exothermaL gas producing starting and sustainirg'decomposition fora multiplicity decomposition. :Theqmetal coating,vbeing truly cataof times with hydrazine type'monopropellant fuels.lytic,ais.not consumed. After combustion .of the propel- "A furtherobject of this invention is to provide a cata-' lant is completedand thesupportqhas-cooled down to *l'yticbed'that is'relatiVely easy to makeandthat can be ambient temperature, subsequent additions ofhydramadewith varying amounts of the-catalytic agent I zine'ihavesthesame result-Sampleshavebeen tested therein. I successfully dozens oftimes with-hydrazine oyer an exstill further object of {thisinventionisto provide a tended period of time.

*tr'ue' catalytic bed that utilizes chemicalsthatare -rela- The:molybdenum. resinate solution contains from tiilely cheap in comparisonto other true catalytic beds. about' 2-to about. IS -percent by. weightmolybdenum metalto resinate material. Thismolybdenumresinate SUMMARY THEINVENTION solutionis diluted with pureturpentine and preferrably,

? In accordance. withthis invention,-.an inert porous an equalamount byweight.of pure turpentine to-the support'material such as fire brick orvarious corru- "molybdenum resinate solution.. The preferred amount Igated ceramicsis saturated with a molybdenum resinof. molybdenum to--resinate material is about 10 to ate solution, and thereafter, thesolution is decomposed about 15 percent andthe amount of turpentine cansuch as by burning toleave a residue coating of molybvary; Pre-mixedmolybdenum resinate solutions that denum and/or'molybdenum oxides on theinert porous .are'within' the, limits of this invention are commerciallysupport material andthereby form a true catalytic bed. .marketedbyflanovia Liquid Gold Division of Engel- When a monopropellant such ashydrazine (N l-l is hardlndustries Incorporated under the namesMolybbrought into contactwiththe true catalytic bed, a spondenum)Resinate Solution No 8605 approximately ta'neous ex'othermaland gasproducing decomposition 13.3% Mo. and Molybdenum Resinate Solution No.

- occurs. 42 approximately 3.3% Mo. *I DETAILED DESQIRIPTION OFTHE'INVENTION EXAMPLE I -lt'h'as been discovered that molybdenum in theform A coating solution-from the commercially available ofrr'i'olyb'denum resinate solutioncan be used as a material is preparedby dilutingithe as received momeans of depositing a true catalyticcoating of molyblybdenum resinate solution No,, 8605 with an equalden'um and/or-molybdenum oxides onan inert gas genweight of turpentine,pure gumspirits. The inert sup- 'erato'r bed or support. This techniqueis applied to the port material to be coated is saturated with themolyb- *-chem'i-thermo,-type gas generator. Briefly, this gas denumresinateand turpentine solution, and the satugenerator concept involvesthe thermal decomposition rated support is ignited with a match orsplint. After the of anexothermic 'monopropellant such ashy'drazine oniv burning has ceased and the solvent has burned off and a porous bed'orsupport such-as insulating .fire brick or presumablythe organic partofthe metal resinate, the "various corrugated ceramics. The scheme dependson winert support materialremains with a coating of molyba hyperg olic'reaction between the propellant and a wdenumand/or molybdenum oxides.One application of 1 chemical-initiator toheat'the bed to a temperatureat a the-turpentine-metal resinate solution to theinert sup- .which thepropellant will sustain thermal decomposiport material such asinsulating firebrick and subsetion on thehot surface. quent burningleaves an approximately 6 to 10 percent The metal that -has been foundto be very successful coating on'theinert support material, whichcoating is as a true catalyst is molybdenumdeposited from a moactivetowards hydrazine.

Two applications, followed by burning after each, leaves approximately a20 to 22 percent, by weight, coating on the inert support material. Thiscatalyst, thus prepared, also brings about spontaneous decomposition ofhydrazine. Thus, the amount of coating of active catalytic material onthe support may be varied by the amount of dilution done, if any, of theas received metal resinate or by making repeated applications of thediluted metal resinate to the support with burning off of the solventand organic material following each application.

EXAMPLE I] Molybdenum resinate may be prepared from abietic acid (resinacid) by dissolving abietic acid in alcoholic potassium hydroxide (0.5NKOH in 95 percent ethanol). To the alcoholic potassium abietate solutionis added a solution of molybdenum pentachloride in methanol (1 M MoCl Adeep blue precipitate is formed which is removed by vacuum filtration.The precipitate is washed on the filter with several small portions ofwater and then air dried. The precipitate, after drying, is dissolved inturpentine to form a molybdenum resinate coating solution. Themolybdenum resinate solution may contain 1 to weight percent of theprecipitate to the turpentine.

As in Example I, the inert support material to be coated is saturatedwith the molybdenum resinate and turpentine solution, and the saturatedsupport is ignited with a match or splint. After burning has ceased andthe solvent has burned off and presumably the organic part of the metalresinate, the inert support material remains with a coating ofmolybdenum and/or molybdenum oxides. One application of theturpentine-metal resinate solution to the inert supportmaterial such asinsulating fire brick and subsequent burning leaves an approximately 6to 10 percent coating on the inert support material, which coating isactive towards hydrazine.

Two applications, followed by burning after each, leaves approximately ato 22 percent, by weight, coating on the inert support material. Thiscatalyst, thus prepared, also brings about spontaneous decomposition ofhydrazine. Thus, the amount of coating of active catalytic material onthe support may be varied by the amount of dilution with turpentine orby making repeated applications of the diluted metal resinate to thesupport with burning off of the solvent and organic material followingeach application.

The catalyst which is prepared as described herein is very active withrespect to bringing about the spontane ous, exothermal, gas producingdecomposition of hydrazine. The catalyst maintains its activity uponrepeated firings with hydrazine even upon long periods'of cool downbetween firings. It has been observed that" there is some slight weightloss in the catalyst upon re peated firings with hydrazine. A sample ofthe catalyst has been fired at least 36 times over a period of severalweeks with little, if any, reduction in activity toward hydrazine.

The catalyst described herein is slowly reactive towards the propellantMHF-3 (86 percent methylhydrazine and 14 percent hydrazine) when testedat room temperature.

The real advantages of this gas generator catalyst over other gasgenerator catalysts is a combination of low cost and the ability tospontaneously decompose the storable hydrazine propellants. The truecatalyst disclosed herein appears far superior in its reaction withthese storage propellants to any of the commercially availablecatalysts.

We claim:

1. The method of making a catalytic bed for a gas generator comprisingsaturating an inert porous support material of porous fire brick orcorrugated ceramic with a solution of equal parts by weight of molyb-.denum resinate and turpentine, and decomposing the solution by burningto leave a coating on the inert porous support material.

2. The method of making a catalytic bed as set fort in claim 1, whereinsaid coating contains molybdenum.

3. The method of making a catalytic bed as set forth in claim 1, whereinsaid coating contains molybdenum and molybdenum oxides.

4. The method of making a catalytic bed as set forth in claim 1, whereinsaid porous fire brick has a porosity from 50 to percent and saidcorrugated ceramic has an overall porosity of from 60 to 90 percent.

2. The method of making a catalytic bed as set forth in claim 1, whereinsaid coating contains molybdenum.
 3. The method of making a catalyticbed as set forth in claim 1, wherein said coating contains molybdenumand molybdenum oxides.
 4. The method of making a catalytic bed as setforth in claim 1, wherein said porous fire brick has a porosity from 50to 80 percent and said corrugated ceramic hAs an overall porosity offrom 60 to 90 percent.